1. Field of the Invention
The present invention pertains to powered surgical tissue cutting instruments that have irrigation systems for supplying irrigation fluid to an internal operative site in a patient's body. More particularly, the present invention pertains to powered surgical tissue cutting instruments in which irrigation fluid is supplied through an irrigation channel that is external to the internal passage of a tubular outer member of the instrument.
2. Discussion of the Related Art
Powered surgical tissue cutting instruments in which an elongate inner member is rotated within the internal passage of an elongate tubular outer member are widely used in various surgical procedures for tissue removal or cutting. Such instruments are particularly well suited for use in endoscopic or minimally invasive surgical procedures carried out under visualization provided by an endoscope. In endoscopic or minimally invasive surgical procedures, the endoscope and other necessary instruments are introduced at an internal operative site in a patient's body via one or more natural or artificially created anatomical portals of relatively small size. Typically, the tubular outer member of the powered surgical tissue cutting instrument has a distal end with an opening, and the inner member thereof has a distal end with a cutting element exposed from the opening to contact anatomical tissue at the internal operative site. Normally, the outer member extends through a portal with the inner member within the outer member to position the cutting element at the internal operative site while proximal ends of the outer and inner members are maintained externally of the patient's body. The proximal ends of the outer and inner members are typically mounted to a powered surgical handpiece having a motor for rotating the inner member within the internal passage of the outer member so that the cutting element is rotated in order to effectuate removal or cutting of anatomical tissue at the internal operative site. It is generally desirable for the outer member to have an outer diameter as small in size as practicable so that the outer member can be introduced at the internal operative site through a portal that is minimized in size to reduce trauma to the patient.
Powered surgical tissue cutting instruments in which the inner member is rotated within the outer member may be referred to as rotary powered surgical tissue cutting instruments. Rotary powered surgical tissue cutting instruments may be designed as straight rotary powered tissue cutting instruments, wherein the outer member extends longitudinally from the handpiece to its distal end with a straight configuration and the inner member likewise has a longitudinally straight configuration of the outer member. In many surgical procedures, however, it is beneficial for rotary powered surgical tissue cutting instruments to be designed as curved or angled rotary powered surgical tissue cutting instruments to better access internal operative sites that are difficult to access with straight rotary powered surgical tissue cutting instruments. In such procedures, curved or angled rotary powered surgical tissue cutting instruments make it possible to properly introduce, position and manipulate the cutting element at the internal operative site quicker with improved visibility and with less trauma to the patient than straight rotary powered surgical tissue cutting instruments. Instruments that are known as curved or angled rotary powered surgical tissue cutting instruments are those in which the central longitudinal axis of the tubular outer member has at least one curve, angle or bend between the handpiece and the outer member distal end, and the inner member conforms to the curved, angled or bent configuration of the outer member while being rotated therein.
The cutting element at the distal end of the inner member in rotary powered surgical tissue cutting instruments can have various configurations depending on the type of anatomical tissue to be removed and/or depending on the type of cutting action to be performed with the instrument. In some rotary powered surgical tissue cutting instruments, the cutting element at the distal end of the inner member cooperates with a cutting element at the distal end of the outer member to cut anatomical tissue as a result of the inner member cutting element being rotated past the outer member cutting element. In other rotary powered surgical tissue cutting instruments, the cutting element at the distal end of the inner member includes a bur tip exposed from the opening in the distal end of the tubular outer member.
It is common for rotary powered surgical tissue cutting instruments to include irrigation systems for supplying irrigation fluid to the internal operative site. In curved rotary powered surgical tissue cutting instruments, the irrigation fluid is often supplied through a separate irrigation tube that is external to the tubular outer member and that extends alongside the external or outer diameter surface of the tubular outer member as represented by U.S. Pat. No. 6,312,438 B1 to Adams and U.S. Pat. No. 6,656,195 B2 to Peters et al. The irrigation tube is ordinarily attached to the outer member and/or to the powered handpiece. Irrigation fluid is supplied to the irrigation tube through a proximal inlet and is discharged from the irrigation tube through a distal outlet. In use, the irrigation tube extends through the anatomical portal alongside the outer member of the instrument, with the proximal inlet of the irrigation tube being disposed external of the patient's body for connection with a source of irrigation fluid, and the distal outlet of the irrigation tube being disposed near the distal end of the outer member for discharge of the irrigation fluid at the internal operative site.
The external irrigation tube adds bulk, mass, weight, size and volume to the rotary powered surgical tissue cutting instrument that may cause or contribute to surgeon fatigue while holding the instrument via the handpiece and/or may make it more difficult for the surgeon to properly manipulate the instrument via the handpiece. In order to accommodate the external cross-sectional size and configuration of the composite structure formed by the outer member and the external irrigation tube, the anatomical portal used for introduction of the instrument may need to be larger in size than would otherwise be required. The need for an anatomical portal of increased size is generally undesirable on account of the additional patient trauma associated therewith. Furthermore, the additional space taken up by the external irrigation tube may decrease or impair visibility of the internal operative site by the surgeon and/or reduce the amount of available free area or room within the patient's body available to the surgeon for maneuvering the instrument and/or the endoscope.